1. Field of the Invention
This invention relates to covers for drums or vertical containers holding hazardous waste materials which are to be prevented from escaping into the environment, such as waste oils. Still, more particularly, the invention relates to open head containers having a cover which may be sealably attached and detached to the container such as through the use of a sealable, hinged lid thereupon.
2. Description of the Prior Art
Drums used in the waste industry to contain and store potentially hazardous wastes, such as waste oils, are typically 55 gallon or 30 gallon drums. Two general types of containers are common in the hazardous waste industry. These two types are open head containers and closed head containers. Closed head containers have a nonremovable top with a relatively small opening in that top. Waste materials are able to be entered into the container through the small opening, usually through the use of some type of funnel. Open head containers are containers in which the cover is substantially the same width as the drum and may be attached and detached from the container.
Open head containers utilize a flat cover which mates to the drum. Unsealed lids can be used which sit on a drum and are thus easily removed. Such unsealed lids carry the risk that hazardous material will exit the drum. Thus, the industry utilizes covers for open head containers which may be sealably secured to the drum.
Sealably securing the cover to the drum is necessary because certain potentially hazardous wastes must be placed in sealed containers. For example, volatile organic compounds must often be placed in the containers. Thus, the waste container must have a top which can be sealed to the drum in order to prevent the volatile organic compounds from exiting the container and entering the environment. Typically, the cover is secured to the drum by means of a bolt ring. In operation, the bolt ring is placed around the cover and the drum. Then, bolts are engaged with the bolt ring so as to tighten down the bolt ring around the cover and the drum.
In addition to being sealable, the cover must be removable, because materials often must be added to the drums at incremental stages. With covers currently available for use with open head containers, it is difficult to know if a proper seal has been attained. In an effort to make the sealing of the drum easier, devices such as rams have been employed, which press the bolt ring to the drum. The more often a cover is removed and resecured to a drum, the more likely that an improper seal will exist between the cover and the drum. In any event, removing the entire cover and resecuring it with a bolt ring is relatively time consuming.
Therefore, it would be advantageous to provide a cover that may be sealed to the waste container and remain sealed throughout the period in which materials are added to the drum. It would be further advantageous for such a drum to be capable of being opened and closed easily so as to allow materials to be added to the drum when necessary.